On a Jenkins instance without any front end modifications the layout on analysis report pages slightly changes. It seems that only the body font-size for breadcrumbs and username / login section are affected.

Comparing the style on a regular page with the analysis report page, I noticed that some elements get their style.css replaced by a _reboot.scss. This causes the body font-size to appear in 1rem instead of 13px which makes a clearly visible change.